Conventionally an electric vehicle is fitted with high-voltage batteries delivering a direct current to an inverter which converts this direct current into an alternating current making it possible to power an electric motor, the latter setting the vehicle in motion.
So as to recharge these high-voltage batteries, it is known practice to fit the vehicle with an onboard charging device essentially comprising an alternating current-direct current converter making it possible to rectify the alternating power of the electricity network in order to charge the batteries. Advantageously, the device also comprises a direct current-direct current converter ensuring that the voltage level of the network is matched to that of the batteries.
The electronic components of the powering system on the one hand and of the charging system on the other hand are costly. Moreover, the motor is powered and the batteries are charged at different phases so it has been proposed, in applications EP 0 603 778 and WO97/08009, to reuse a portion of the motor and of the components used to power it in order to produce the device for charging the batteries.
Accordingly, the device for charging the batteries uses the inverter to form an alternating current-direct current converter and the windings of the motor to form the inductors. The transition from the motor-powering mode to that of charging the batteries is carried out by power contactors by disconnecting the neutral.
Using power connectors is however problematic in the sense that, conveying the currents of the electric machine, they must be oversized. Specifically, as an example, a 50 kW traction system powered by 345 V nominal batteries may require a current of approximately 350 A root mean square in order to provide a maximum torque. If the rotor blocks up, this current may reach a peak of 500 A while sustaining vibrations and impacts to which motor vehicles according to the applicable standards may be subjected.